Public Class Form1
 
    Dim r1 As Integer
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
 
        r1 = Val(TextBox1.Text)
        TextBox2.Text = r1 + 10
 
        If (Val(TextBox2.Text) >= 60) Then
            Exit Sub
 
        End If
    End Sub
End Class

Public Class Form1
 
    Dim r1 As Integer
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
 
        r1 = Val(TextBox1.Text)
'te refieres a esto
 
if r1+10 < 80 then 'si es menor a 80 se cumnple
        TextBox2.Text = r1 + 10
 
        If (Val(TextBox2.Text) >= 60) Then
            Exit Sub
 
        End If
endif 'cierro
    End Sub
End Class